Portion of a toothbrush



FIG. 1 is a perspective view showing a front and right side of a portion of a toothbrush showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a left-side view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a right-side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is a perspective view showing a front and right side of another embodiment of a portion of a toothbrush;

FIG. 9 is a front view thereof;

FIG. 10 is a left-side view thereof;

FIG. 11 is a rear view thereof;

FIG. 12 is a right-side view thereof;

FIG. 13 is a top view thereof; and,

FIG. 14 is a bottom view thereof.

The broken lines are shown for environmental purposes and form no part of the claimed design. 

The ornamental design for a portion of a toothbrush, as shown and described. 